Aluminum pigment, process for its production and resin compositions containing the same

ABSTRACT

An aluminum pigment excellent in water resistance useful in water metallic paints, water metallic inks and the like is provided.  
     An aluminum pigment excellent in water resistance has a coating derived from peroxo-polymolibdate represented by the compositional formula: 
     MoO 3 .mH 2 O 2 .nH 2 O or MoO 3-m (O 2 ) m .nH 2 O 
     wherein Mo is molybdenum, O is oxygen, 0≦m≦1 and 1≦n≦2 and comprises at least one amine selected from alkylamine, allylamine, arylamine, alkanolamine and alkoxylamine.

TECHNICAL FIELD

[0001] The present invention relates to aluminum pigments useful inwater metallic paints, water metallic inks or the like, method for theirpreparation and resin compositions containing them.

PRIOR ARTS

[0002] The incorporation of aluminum pigments into aqueous varnishescauses various problems such as an explosion of a container duringstorage due to the reaction with water contained in the varnishes toproduce hydrogen gas and an agglomeration of the aluminum pigment toform grainings. Many techniques for resolving the problems have beendeveloped. Among them, JP-B-89/054386 (1989), JP-A-59/074201 (1984),JP-B-85/008057 (1985), JP-A-04/318181 (1992), U.S. Pat. No. 5,296,032,JP-A-06/057171 (1994) and JP-A-09/328629 (1997) are known as recenttechniques having high possibility of practical use.

[0003] JP-B-89/054386 (1989) discloses a method comprising treating analuminum pigment with chromic acid. Although chemical stability of thealuminum pigment is improved according to the method, the method hasproblems such that the aluminum pigment in the finely divided formcannot be treated due to a strong reactivity of the treating liquid usedand that the hygiene for operators and environment are damaged by usinghexavalent chromium. Thus, the above method is not almost subjected tothe practical use.

[0004] JP-A-59/074201 (1984) discloses a method comprising treating analuminum pigment with ammonium vanadate. Color tone of the aluminumpigment is significantly changed by this treatment. Thus, the abovemethod has not been practically applied.

[0005] JP-B-85/008057 (1985) discloses a method comprising coating analuminum pigment with an acid phosphate ester. Although color tone andchemical stability of the aluminum pigment are better, the treatingagent adversely affects an adhesion between the aluminum pigment and aresin when a film is formed according to the two-coat/one-bake coatingmethod or the two-coat/two-bake coating method so that a base metallicfilm and a top coat will be delaminated, which becomes problematic.

[0006] JP-A-04/318181 (1992) discloses a method comprising treating analuminum pigment with a treating liquid containing an oxidizing agentsuch as molybdic acid, a phosphate ion and an alkaline earth metal ion.Although the resultant aluminum pigment has excellent chemicalstability, the phosphate ion and the alkaline earth metal ion containedin the treating liquid tend to lower physical properties including amoisture resistance of a film.

[0007] U.S. Pat. No. 5,296,032 discloses a method comprising treating analuminum pigment with a heteropolyanion such as phosphomolybdic acid andthe like. Although the aluminum pigment treated with phosphomolybdicacid is chemically stable, the phosphate ion contained in the treatingliquid lowers physical properties including a moisture resistance of afilm. Sufficient chemical stability is not obtained when any othertreating agent is used.

[0008] JP-A-06/057171 (1994) discloses a method for stabilizing analuminum pigment comprising treating the aluminum pigment with ammoniummolybdate and then adding molybdate salt or the like. Although theresultant aluminum pigment has excellent chemical stability and theresultant film has better physical properties, the preparation processis complicated.

[0009] JP-A-09/328629 (1997) discloses an aluminum pigment treated withperoxo-polyanion. Since a coating derived from peroxo-polyanion is denseand has excellent corrosion resistance, an aluminum pigment which ischemically very stable to a varnish for water paints and water inks canbe obtained by forming the coating on a surface of the aluminum pigment.In addition, since a component adversely affecting physical propertiesof a film such as a phosphate ion and an alkaline earth metal ion is notcontained in the coating, moisture- and weather-resistances of theresultant film are not lowered even by incorporating the aluminumpigment having the above coating. Thus, the aluminum pigment isexcellent chemical stability together with better physical properties ofa film, but it has problems such that the aluminum pigment tends to beagglomerated during its preparation so that grainings are produced onthe resultant film or it adversely affects an appearance of theresultant film. Thus, the above aluminum pigment is not practicallyapplied.

SUMMARY OF THE INVENTION

[0010] The present inventors investigated to form a better coatingderived from peroxo-polyanion on a surface of an aluminum pigmentwithout agglomelating the aluminum pigment during its preparation. Asthe result, they found that it is effective to add at least one amineselected from alkylamine, allylamine, arylamine, alkanolamine andalkoxylamine to peroxo-polymolibdate and the chemical stability of theresultant coating and the prevention of an aluminum pigment fromagglomerating can be improved by forming an adsorption layer of anorganic phosphorus compound onto the coating.

DETAILED EXPLANATION OF THE INVENTION

[0011] According to the present invention made based on these findings,the aluminum pigment excellent in water resistance comprises at leastone amine selected from alkylamine, allylamine, arylamine, alkanolamineand alkoxylamine and has a coating derived from polymolybdic acidperoxide formed on a surface thereof.

[0012] Preferably, 0.025 to 5 parts by weight of molybdenum (Mo) and0.08 to 20 parts by weight of oxygen (O) are contained per 100 parts byweight of aluminum.

[0013] It is preferable to further have an adsorption layer of anorganic phosphorus compound which is preferably an acidic phosphateester derived from an aliphatic monohydric or polyhydric alcoholcontaining 4 to 18 carbon atoms, on the inorganic coating.

[0014] The aluminum pigment of the present invention is prepared byadding to an aluminum pigment composition containing an organic solvent,at least one amine selected from alkylamine, allylamine, arylamine,alkanolamine and alkoxylamine together with a solution of a metallicmolybdenum dissolved in an aqueous hydrogen oxide and a hydrophilicsolvent and then stirring and mixing to form an inorganic coating on asurface of the aluminum and if necessary, adding an organic phosphoruscompound before getting paste.

[0015] Further, the resin composition according to the present inventionis obtained by adding the aluminum pigment of the present invention.

[0016] Several essential features of the present invention and thereason for the numerical limitation of each essential feature are fullydescribed below.

[0017] (1) Peroxo-polymolibdate

[0018] The peroxo-polymolibdate used in the present invention isrepresented by the compositional formula:

MoO₃.mH₂O₂.nH₂O or MoO_(3-m)(O₂)_(m).nH₂O

[0019] wherein Mo is molybdenum, O is oxygen, 0≦m≦1 and 1≦n≦2. Asolution comprising polymolybdic acid peroxide having the abovecomposition is prepared by the method comprising dissolving a metallicmolybdenum in hydrogen oxide as described in, for example, Solid StatesIonics, pp. 507-512, 1992. Owing to peroxo-polymolibdate having theabove composition, a coating excellent in chemical stability can beformed on a surface of the aluminum pigment. And, such a pigment doesnot lower physical properties of the resultant film even if incorporatedinto a resin composition.

[0020] (2) Mo (Molybdenum) Content

[0021] The Mo content in the coating formed on the surface of thealuminum pigment is 0.02 to 5 parts by weight per 100 parts by weight ofaluminum. If it is less than 0.02 part by weight, the desired chemicalstability is hardly obtained. On the other hand, if it is above 5 partsby weight, the aluminum pigment agglomerates so that its design and itshiding property are impaired. Although JP-A-09/328629 (1997) describesthat an amount of a metallic element is most suitably in the range from0.01 to 2 parts by weight per 100 parts by weight of aluminum, theagglomeration of the aluminum pigment does not occur even if the amountof peroxo-polymolibdate is further increased, thereby a thicker coatingwith an improved chemical stability can be formed according to thepresent invention.

[0022] Preferably, the Mo content will be varied depending on a watercovering area of the aluminum pigment. Specifically, it is preferable tosatisfy the following equation within the above range.

0.2×S≦Mo≦2×S

[0023] wherein Mo is the Mo content (parts by weight per 100 parts byweight of aluminum) and S is a water covering area of the aluminumpigment (m²/g).

[0024] (3) O (Oxygen) Content

[0025] The O content in the coating formed on the surface of thealuminum pigment is 0.08 to 20 parts by weight per 100 parts by weightof aluminum. If it is less than 0.08 part by weight, the desiredchemical stability is hardly obtained. On the other hand, if it is above20 parts by weight, the aluminum pigment agglomerates so that its designand its hiding property are impaired.

[0026] (4) Alkylamine, Allylamine, Arylamine, Alkanolamine andAlkoxylamine

[0027] When the aluminum pigment is treated merely withperoxo-polymolibdate, both are reacted vigorously so that the aluminumpigment is agglomerated. Thus, at least one amine is added to controlthe reaction between the aluminum pigment and peroxo-polymolibdate andto prevent the aluminum pigment from agglomerating. Since the amineforms a salt with polymolybdic acid peroxide, a passive coating can beobtained.

[0028] Example of the amine to be added includes methylamine,ethylamine, propylamine, isopropylamine, butylamine, amylamine,hexylamine, heptylamine, octylamine, nonylamine, decylamine,undecylamine, dodecylamine, tridecylamine, tetradecylamine,pentadecylamine, cetylamine, dimethylamine, diethylamine, dipropylamine,diisopropylamine, dibutylamine, diamylamine, trimethylamine,triethylamine, tripropylamine, tributylamine, triamylamine, allylamine,diallylamine, triallylamine, cyclopropylamine, cyclobutylamine,cyclopentylamine, cyclohexylamine, aniline, methylaniline,dimethylaniline, ethylaniline, diethylaniline, o-toluidine, m-toluidine,p-toluidine, benzylamine, dibenzylamine, tribenzylamine, diphenylamine,triphenylamine, α-naphtylamine, β-naphthylamine,3,3′-iminobis(propylamine), 2-ethylhexylamine,3-(2-ethylhexyloxy)propylamine, 3-ethoxypropylamine,3-(diethylamino)propylamine, di-2-ethyhexylamine,3-(dibutylamino)propylamine, tetramethylethylenediamine,tri-n-octylamine, 3-(methylamino)propylamine,3-(dimethylamino)propylamine, N-methyl-3,3′-imino-bis(propylamine),3-methoxypropylamine, 2-dimethylaminoethanol, monoethanolamine,diethanolamine, triethanolamine, 2-amino-2-methyl-1-propanol,N,N-dimethyl-1,3-propanediamine and morpholine.

[0029] Among them, 2-dimethylaminoethanol, triethanolamine,3-(2-ethylhexyloxy)propylamine, 3-ethoxypropylamine, dibutylamine and2-ethylhexylamine are particularly preferable.

[0030] An added amount of the amine is 0.02 to 10 parts by weight,preferably 0.1 to 5 parts by weight, per 100 parts by weight ofaluminum. If it is less than 0.02 part by weight, the agglomeration ofthe aluminum pigment occurs. On the other hand, if it is above 10 partsby weight, physical properties such as adhesion, weather resistance,moisture resistance, water resistance and the like are lowered.

[0031] Preferably, the added amount of the amine will be varieddepending on the Mo content in the coating formed on the surface of thealuminum pigment. Specifically, it is preferable to satisfy thefollowing equation within the above range.

1×Mo≦A≦4×Mo

[0032] wherein A is the added amount of the amine (parts by weight per100 parts by weight of aluminum) and Mo is the Mo content (parts byweight per 100 parts by weight of aluminum).

[0033] (5) Organic Phosphorus Compound

[0034] The organic phosphorus compound can enhance the chemicalstability of the coating and the prevention of the aluminum pigment fromagglomerating. Further, it can improve a dispersion of the aluminumpigment in a paint and a color tone of the aluminum pigment. Since theorganic phosphorus compound scarcely contains a phosphate ion, it doesnot adversely affect physical properties of the film.

[0035] Example of the preferable organic phosphorus compound includesacidic phosphate esters, polyoxyethylene alkylphenol phosphoric acids,phosphate esters obtained by reacting epoxy compounds or acryliccompounds with phosphoric acid, and (meth)acrylic phosphate esters.

[0036] Particularly preferable compound is an acidic phosphate esterderived from an aliphatic monohydric or polyhydric alcohol containing 4to 18 carbon atoms. Such an acidic phosphate ester is a mixture of amonoester of an orthophosphoric acid with an aliphatic alcoholrepresented by R—O—PO(OH)₂ and a diester of an orthophosphoric acid withan aliphatic alcohol represented by (R—O)₂—PO(OH). Specific examplethereof includes stearyl acid phosphate, myristyl acid phosphate,palmityl acid phosphate, lauryl acid phosphate, polyoxyethylenealkylphenylether acid phosphate, n-dodecyl acid phosphate, 2-ethylhexylacid phosphate, oleyl acid phosphate, hexyl acid phosphate, butyl acidphosphate, ethylene glycol acid phosphate, mono(2-acryloyloxyethyl) acidphosphate, mono(2-methacryloyloxyethyl) acid phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate and(2-hydroxyethyl)methacrylate acid phosphate.

[0037] A polymer is included in the scope of the organic phosphoruscompound.

[0038] Example of the preferable polymer is epoxy resins, acrylicresins, alkyd resins, polyester resins, bisphenol-type epoxy resins,novolak-type epoxy resins, polyester polyol resins, polyoxyalkylenepolyol resins, phenol resins, rosin modified phenol resins, xyleneresins, ketone resins, melamine resins, urea resins, polyamide resins,polyamide polyamine epichlorohydrin resins, polyurethane resins,polyvinyl acetate resins, vinyl ester resins, nitrocellulose resins,fluoro resins, alicyclic hydrocarbon resin and their copolymers, towhich phosphate groups are introduced.

[0039] A method of introducing a phosphate group into the above resinincludes a method comprising acting a phosphoric acid or an alkylphosphate onto an epoxy or hydroxyl group in the resin; and a methodcomprising polymerizing a polymerizable monomer containing a phosphategroup with a precursor monomer constituting the skeleton of the aboveresin.

[0040] The polymer has preferably an average molecular weight rangingfrom 400 to 10,000. If it has the molecular weight of less than 400, theimprovement in adhesion of the resultant film cannot be expected. On theother hand, if it has the molecular weight above 10,000, it lowers thestability of the aluminum pigment for which the agglomeration of thealuminum pigment may occur. Specific example of the polymer includes:

[0041] an adduct of an alicyclic epoxy compound (“CEL 2081” (trade name)manufactured by Daicel Chemical Ind.) with a phosphorus compound, calledas “2081PO”, based on the ingredient represented by the followingstructure I:

[0042] and having an average molecular weight of about 1,100.Preferably, the alicyclic epoxy compound has a molecular weight rangingfrom about 300 to about 1,000, especially from about 700 to about 1,000and an epoxy equivalent ranging from about 150 to about 500, especiallyfrom about 350 to about 500; and

[0043] an adduct of an alicyclic epoxy compound (neopentyl glycoldiglycidyl diether manufactured by Daicel Chemical Ind.) with aphosphorus compound, called as “NPG-PO”, based on the ingredientrepresented by the following structure II:

[0044] and having an average molecular weight of about 410. Preferably,the alicyclic epoxy compound has a molecular weight ranging from about150 to about 1,000, especially from about 180 to about 400 and an epoxyequivalent ranging from about 100 to about 600, especially from about120 to about 250.

[0045] Preferable added amount of the organic phosphorus compound is 0.1to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100parts by weight of aluminum. If it is less than 0.1 part by weight, thedesired effect is not obtained. On the other hand, if it is above 10parts by weight, physical properties such as adhesion, weatherresistance, moisture resistance and the like are adversely affected.Further, this amount will be varied depending on a water covering areaof the aluminum pigment. Specifically, it is preferable to satisfy thefollowing equation within the above range.

0.2×S≦P≦2×S

[0046] wherein P is the added amount of the organic phosphorus compound(parts by weight per 100 parts by weight of aluminum) and S is a watercovering area of the aluminum pigment (m²/g).

[0047] (6) Method for Preparation

[0048] A method comprising adding to an aluminum pigment compositioncontaining any organic solvent, at least one amine selected fromalkylamine, allylamine, arylamine, alkanolamine and alkoxylaminetogether with a solution comprising peroxo-polymolibdate obtained byadding a metallic molybdenum dissolved in an aqueous hydrogen oxide anda hydrophilic solvent, stirring and mixing to form an inorganic coatingon a surface of the aluminum and if necessary, adding an organicphosphorus compound before getting paste is preferable since thepreparation process is simple, provided that methods for preparation ofthe aluminum pigment are not limited thereto. It is desirable to controlthe reaction by adjusting conditions such as temperature, pressure andhumidity if necessary during stirring and mixing.

[0049] As the aluminum pigment composition containing any organicsolvent, the conventional aluminum paste is preferably used. Thealuminum paste as used herein means a pasty composition comprising aflaky aluminum to which any organic solvent such as mineral sprit isadded in an amount of 10 to 100 parts by weight per 100 parts by weightof the aluminum and having an adsorption layer of a fatty acid such asoleic acid or stearic acid on a surface of the aluminum. Desirably, thefatty acid is previously removed as much as possible by washing or thelike.

[0050] The method for adding the amine is not particularly limited.Generally, the amine is dissolved in an organic solvent such as mineralspirit, alcohol or the like before the addition.

[0051] The solution comprising peroxo-polymolibdate represented by thecompositional formula:

MoO₃ .mH₂O₂ .nH₂O or MoO_(3-m)(O₂)_(m) .nH₂O

[0052] wherein Mo is molybdenum, O is oxygen, 0≦m≦1 and 1≦n≦2 isprepared by dissolving a metallic molybdenum in an aqueous hydrogenperoxide containing hydrogen peroxide, as described above. Depending onthe concentration of the aqueous hydrogen peroxide, the values of m andn as well as crystalline structure, color and solubility in water ofpolymolybdic acid peroxide will be changed. According to the experimentof the present inventors for finding the condition suitable for theformation of the inorganic coating which improves the water resistanceof the aluminum pigment, the method comprising dissolving 1 to 50% byweight, preferably 5 to 20% by weight, of a metallic molybdenum or amolybdenum compound such as molybdenum oxide, molybdenum alkoxide andthe like in an aqueous hydrogen oxide at the concentration of 1 to 70%by weight, preferably 5 to 50% by weight is suitable. If the aqueoushydrogen peroxide has a lower concentration, the metallic element ishardly dissolved. On the other hand, the use of the aqueous hydrogenperoxide having a higher concentration is dangerous since vigorousreaction occurs upon the addition of the metallic element. If themetallic element has a lower concentration, the desired effect is hardlyobtained. On the other hand, if it has a higher concentration, it is notcompletely dissolved in the aqueous hydrogen peroxide. Desirably, thesolution comprising polymolybdic acid peroxide is diluted in ahydrophilic solvent such as an alcohol or the like before its addition.Preferable example of the usable hydrophilic solvent includes methylalcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butylalcohol, isobutyl alcohol, acetone, ethyl cellosolve, propylene glycolmonomethyl ether, dipropylene glycol monomethyl ether and the like.

[0053] In order to improve a dispersibility of the aluminum pigment in apaint and an affinity thereof to a resin and/or to further improve acorrosion resistance of the aluminum pigment, any surfactant such aspolyoxyethylene alkyl phenol ether, polyoxyethylene alkylamine,alkylbenzene sulfonate salt and the like and any other corrosioninhibitor such as a dimer acid and the like may be added to the surfaceof the aluminum pigment of the present invention.

[0054] The aluminum pigment of the present invention is used as a resincomposition to be incorporated in paints, inks and the like. The resincomposition as used herein includes paints and films made therefrom aswell as inks and printed matters made thereby. The paint or the inkbased on an organic solvent or water is usable, but the use of a waterpaint or a water ink is particularly suitable in the present inventionin view of the purpose of the present invention. An amount of thealuminum pigment to be incorporated in the resin composition is suitably0.1 to 30% by weight based on the total weight of the resin composition.If it is less than 0.1% by weight, sufficient decorative (metallic)effect is not obtained. On the other hand, if it is above 30% by weight,physical properties such as weather resistance, corrosion resistance,mechanical strength and the like of the resin composition are adverselyaffected.

[0055] Paints and inks consist of the following components:

[0056] 1) resin: acrylic resins, alkyd resins, polyester resins,polyurethane resins, polyvinyl acetate resins, nitrocellulose resins,fluroresins;

[0057] 2) pigment: in addition to the aluminum pigment of the presentinvention, color pigments, extender pigments and/or dyes such asphthalocyanine, quinacridone, isoindolinone, perylene, azo lake, ironoxide, chrome yellow, carbon black, titanium oxide, pearl mike and thelike; and

[0058] 3) additives: water, organic solvents, surfactants, curingagents, UV absorbers, static removers, thickeners and the like.

[0059] The resin composition of the present invention may be applied toan undercoat or an intermediate coat by any suitable method includingthe electrodeposition coating to form a film. The film may be coatedwith a top coat. Action and Effect The aluminum pigment of the presentinvention is chemically stable and therefore it can be suitably used inwater paints and water inks. And, the agglomeration of the aluminumpigment which is the problem caused by treating with polyacid peroxidein the prior art can be resolved.

[0060] The method of preparing the aluminum pigment of the presentinvention is simple in steps and therefore the aluminum pigment of thepresent invention can be prepared with a low cost.

[0061] The resin composition of the present invention has excellentstorage stability as water paints and water inks so that the productionof a hydrogen gas during storage and the agglomeration of an aluminumpigment are not observed. The resultant film and printed matter isexcellent in terms of physical properties including moisture resistance.

EXAMPLES Example 1

[0062] Solvents were removed from the commercially available aluminumpigment (7640NS manufactured by Toyo Aluminium K.K.; non-volatilecontent =65%; water covering area=1.1 m²/g) to prepare a cake having anon-volatile content of 80% (hereinafter referred to as “7640NS cake”).To 1 kg of this 7640NS cake, 20 g of 2-dimethylamino ethanol and asolution obtained by adding 8 g of a metallic molybdenum powder in smallportions to 100 g of an aqueous hydrogen peroxide containing 30%hydrogen peroxide and reacting them to prepare a solution which was thendissolved in 175 g of isopropyl alcohol were added and kneaded at 60° C.for 1 hour. Then, 100 g of dipropylene glycol monomethyl ether and 10 gof oleyl acid phosphate were added and further mixed at an ordinarytemperature for 30 minutes before getting a pasty aluminum pigment.

[0063] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.95 part by weight of Mo and3.6 parts by weight of O per 100 parts by weight of aluminum.

Example 2

[0064] To 1 kg of the 7640NS cake used in Example 1, 20 g oftert-butylamine and a solution obtained by adding 8 g of a metallicmolybdenum powder in small portions to 100 g of an aqueous hydrogenperoxide containing 30% hydrogen peroxide and reacting them to prepare asolution which was then dissolved in 175 g of isopropyl alcohol wereadded and kneaded at 60° C. for 1 hour. Then, 100 g of dipropyleneglycol monomethyl ether and 10 g of oleyl acid phosphate were added andfurther mixed at an ordinary temperature for 30 minutes before getting apasty aluminum pigment.

[0065] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.97 part by weight of Mo and3.5 parts by weight of O per 100 parts by weight of aluminum.

Example 3

[0066] To 1 kg of the 7640NS cake used in Example 1, 20 g of3-(2-ethylhexyloxy)propylamine and a solution obtained by adding 8 g ofa metallic molybdenum powder in small portions to 100 q of an aqueoushydrogen peroxide containing 30% hydrogen peroxide and reacting them toprepare a solution which was then dissolved in 175 g of isopropylalcohol were added and kneaded at 60° C. for 1 hour. Then, 100 g ofdipropylene glycol monomethyl ether and 10 g of oleyl acid phosphatewere added and further mixed at an ordinary temperature for 30 minutesbefore getting a pasty aluminum pigment.

[0067] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.99 part by weight of Mo and3.7 parts by weight of O per 100 parts by weight of aluminum.

Example 4

[0068] To 1 kg of the 7640NS cake used in Example 1, 4 g of triethanolamine and a solution obtained by adding 2 g of a metallic molybdenumpowder in small portions to 100 g of an aqueous hydrogen peroxidecontaining 30% hydrogen peroxide and reacting them to prepare a solutionwhich was then dissolved in 175 g of isopropyl alcohol were added andkneaded at 60° C. for 1 hour. Then, 100 g of dipropylene glycolmonomethyl ether and 10 g of oleyl acid phosphate were added and furthermixed at an ordinary temperature for 30 minutes before getting a pastyaluminum pigment.

[0069] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.25 part by weight of Mo and1.76 parts by weight of O per 100 parts by weight of aluminum.

Example 5

[0070] To 1 kg of the 7640NS cake used in Example 1, 20 g of2-amino-2-methyl-1-propanol and a solution obtained by adding 8 g of ametallic molybdenum powder in small portions to 100 of an aqueoushydrogen peroxide containing 30% hydrogen peroxide and reacting them toprepare a solution which was then dissolved in 175 g of isopropylalcohol were added and kneaded at 60° C. for 1 hour. Then, 100 g ofpropylene glycol monomethyl ether and 10 g of hexyl acid phosphate wereadded and further mixed at an ordinary temperature for 30 minutes beforegetting a pasty aluminum pigment.

[0071] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.98 part by weight of Mo and3.9 parts by weight of O per 100 parts by weight of aluminum.

Example 6

[0072] To 1 kg of the 7640NS cake used in Example 1, 40 g ofn-butylamine and a solution obtained by adding of 32 g of a metallicmolybdenum powder in small portions to 200 g of an aqueous hydrogenperoxide containing 30% hydrogen peroxide and reacting them to prepare asolution which was then dissolved in 175 g of isopropyl alcohol wereadded and kneaded at 60° C. for 1 hour. Then, 100 g of dipropyleneglycol monomethyl ether and 10 g of butyl acid phosphate were added andfurther mixed at an ordinary temperature for 30 minutes before getting apasty aluminum pigment.

[0073] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 7.8 part by weight of Mo and11.5 parts by weight of O per 100 parts by weight of aluminum.

Example 7

[0074] To 1 kg of the 7640NS cake used in Example 1, 20 g of morpholineand a solution obtained by adding 8 g of a metallic molybdenum powder insmall portions to 100 g of an aqueous hydrogen peroxide containing 30%hydrogen peroxide and reacting them to prepare a solution which was thendissolved in 175 g of isopropyl alcohol were added and kneaded at 60° C.for 1 hour. Then, 100 g of dipropylene glycol monomethyl ether, 10 g ofoleyl acid phosphate and 20 g of polyoxyethylene nonylphenol ether as asurfactant were added and further mixed at an ordinary temperature for30 minutes before getting a pasty aluminum pigment.

[0075] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.96 part by weight of Mo and3.9 parts by weight of O per 100 parts by weight of aluminum.

Example 8

[0076] To 1 kg of the 7640NS cake used in Example 1, 20 g of3-ethoxypropylamine and a solution obtained by adding 8 g of a metallicmolybdenum powder in small portions to 100 g of an aqueous hydrogenperoxide containing 30% hydrogen peroxide and reacting them to prepare asolution which was then dissolved in 175 g of isopropyl alcohol wereadded and kneaded at 60° C. for 1 hour. Then, 100 g of dipropyleneglycol monomethyl ether was added and further mixed at an ordinarytemperature for 30 minutes before getting a pasty aluminum pigment.

[0077] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.99 part by weight of Mo and4.1 parts by weight of O per 100 parts by weight of aluminum.

Example 9

[0078] To 1 kg of the 7640NS cake used in Example 1, 20 g of3-(2-ethylhexyloxy)propylamine and a solution obtained by adding 8 g ofa metallic molybdenum powder in small portions to 100 g of an aqueoushydrogen peroxide containing 30% hydrogen peroxide and reacting them toprepare a solution which was then dissolved in 175 g of isopropylalcohol were added and kneaded at 60° C. for 1 hour. Then, 100 g ofdipropylene glycol monomethyl ether and 15 g of an adduct (2081-PO) ofan alicyclic epoxy compound (CEL 2081 (trade name) manufactured byDaicel Chemical Ind.) with a phosphorus compound was added and furthermixed at an ordinary temperature for 30 minutes before getting a pastyaluminum pigment.

[0079] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.98 part by weight of Mo and4.2 parts by weight of O per 100 parts by weight of aluminum.

Example 10

[0080] To 1 kg of the 7640NS cake used in Example 1, 20 g of3-(2-ethylhexyloxy)propylamine and a solution obtained by adding 8 g ofa metallic molybdenum powder in small portions to 100 g of an aqueoushydrogen peroxide containing 30% hydrogen peroxide and reacting them toprepare a solution which was then dissolved in 175 g of isopropylalcohol were added and kneaded at 60° C. for 1 hour. Then, 100 g ofdipropylene glycol monomethyl ether and 15 g of an adduct (NPG-PO) of analicyclic epoxy compound (neopentylglycol diglycidyl diethermanufactured by Daicel Chemical Ind.) with a phosphorus compound wasadded and further mixed at an ordinary temperature for 30 minutes beforegetting a pasty aluminum pigment.

[0081] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.98 part by weight of Mo and3.8 parts by weight of O per 100 parts by weight of aluminum.

Comparative Example 1

[0082] To 1 kg of the 7640NS cake used in Example 1, a solution obtainedby adding 8 g of a metallic molybdenum powder in small portions to 100 gof an aqueous hydrogen peroxide containing 30% hydrogen peroxide andreacting them to prepare a solution which was then dissolved in 175 g ofisopropyl alcohol was added and kneaded at 60° C. for 1 hour. Then, 100g of dipropylene glycol monomethyl ether and 10 g of oleyl acidphosphate were added and further mixed at an ordinary temperature for 30minutes before getting a pasty aluminum pigment.

[0083] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.99 part by weight of Mo and4.1 parts by weight of O per 100 parts by weight of aluminum.

Comparative Example 2

[0084] To 1 kg of the 7640NS cake used in Example 1, 20 g oftert-butylamine and a solution obtained by adding 8 g of aphosphomolybdic acid powder containing 8 g of Mo to 100 g of an aqueoushydrogen peroxide containing 30% hydrogen peroxide to prepare a solutionwhich was then dissolved in 175 g of isopropyl alcohol was added andkneaded at 60° C. for 1 hour. Then, 100 g of dipropylene glycolmonomethyl ether and 10 g of oleyl acid phosphate were added and furthermixed at an ordinary temperature for 30 minutes before getting a pastyaluminum pigment.

[0085] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.95 part by weight of Mo and3.5 parts by weight of O per 100 parts by weight of aluminum.

Comparative Example 3

[0086] To a slurry comprising 500 g of the 7640NS cake used in Example 1dispersed in 2,000 ml of propylene glycol monomethyl ether whilestirring, a solution of ammonium paramolybdate containing 4 g of Modissolved in 400 ml of a deionized water was added slowly and reactedfor 1 hour while keeping the slurry at 18° C. The resultant slurry wassolid-liquid separated to obtain a pasty aluminum pigment with a solidcontent of 50%.

[0087] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 0.89 part by weight of Mo and3.1 parts by weight of O per 100 parts by weight of aluminum.

Comparative Example 4

[0088] To 1 kg of the 7640NS cake used in Example 1, a solutioncomprising 10 g of oleyl acid phosphate dissolved in 220 g of mineralspirit was added and kneaded for 30 minutes before getting a pastyaluminum pigment with a solid content of 65%.

[0089] The pasty aluminum pigment was washed with acetone, dried andpowdered to prepare a sample. The Mo content in the sample wasdetermined by inductively coupled plasma specrometer. The O content inthe sample was also determined by the inert gas fusion method. Theresults shows that the sample contained 1.5 parts by weight of 0 per 100parts by weight of aluminum. Mo was not detected.

Examples 11 to 20

[0090] Using each of the aluminum pigments obtained in Examples 1 to 10,a water metallic base paint having the following formulation wasprepared. water soluble acrylic resin ¹⁾ 28.2 g melamine resin ²⁾ 4.4 gtriethanolamine 1.1 g deionized water 44.8 g isopropyl alcohol 3.0 gtransparent iron oxide ³⁾ 5.0 g aluminum pigment 3.0 g (Ex. 1 to 8) (assolid content)

Comparative Examples 5 to 8

[0091] Using each of the aluminum pigments obtained in ComparativeExamples 1 to 4, a water metallic base paint having the formulationidentical with that of Examples 9 to 16 was prepared.

Test 1

[0092] 80 Grams of the water metallic base paint made in each ofExamples 11 to 20 as well as Comparative Examples 5 to 8 was sampled.This sample was stored in a water bath controlled at 50° C. for 7 daysto determine a cumulative volume of hydrogen gas produced.

Test 2

[0093] To a steel plate for test previously electro-deposited with aprimary anticorrosive paint, each of the water metallic base paintprepared in each of Examples 11 to 20 as well as Comparative Examples 5to 8 was air sprayed such that the resultant film had a dry thickness of13 μm and pre-dried at 90° C. for 10 minutes, to which an organicsolvent base paint for top coat having the following composition was airsprayed such that the resultant film had a dry thickness of 40 μm,thereby a metallic coated panel was prepared. acrylic resin ¹⁾ 140 gmelamine resin ²⁾ 50 g Solvesso 100 60 g

[0094] The coated panel immediately after the preparation and exposed toan atmosphere at 50° C. and 100% RH for 7 days were tested for theadhesion according to the method of ASTM D3359B and evaluated by 6-rankscoring. The rank of 4B or more in this test is desirable for practicaluse.

Test 3

[0095] 10 Grams of the aluminum pigment composition prepared in each ofExamples 1 to 10 as well as Comparative Examples 1 to 4 was dispersed inisopropyl alcohol and subjected to a wet screening method using a sieveof 45 μm sieve opening to determine a residue on the sieve.

[0096] The aluminum pigment composition was stored at 50° C. for 7 daysto prepare a sample. 10 Grams of this sample was similarly tested todetermine a residue on the screen.

[0097] Results of Tests 1 to 3 are shown in Table 1. TABLE 1 aluminumTest 3 (residue on sieve: %) pigment immediately after storage at usedafter preparation 50° C. for 7 days Ex.1 0.05 0.05 Ex.2 0.05 0.06 Ex.30.05 0.05 Ex.4 0.05 0.05 Ex.5 0.05 0.05 Ex.6 0.12 0.14 Ex.7 0.05 0.07Ex.8 0.08 0.11 Ex.9 0.05 0.05 Ex.10 0.06 0.08 Comp.Ex.1 1.56 2.98Comp.Ex.2 0.22 1.53 Comp.Ex.3 0.07 0.09 Comp.Ex.4 0.05 0.05 Test2(adhesion) after storage aluminum Test 1 immediately at 50° C., pigment(gas volume: after 100% RH for 7 used ml) preparation days Ex.11 0 5B 5BEx.12 0.1 5B 5B Ex.13 0 5B 5B Ex.14 0.5 5B 5B Ex.15 0.1 5B 5B Ex.16 0 5B4B Ex.17 0.3 4B 4B Ex.18 1 5B 5B Ex.19 0.3 5B 5B Ex.20 0 4B 4B Comp.Ex.52.5 5B 5B Comp.Ex.6 3.8 4B 3B Comp.Ex.7 2.8 5B 4B Comp.Ex.8 7.3 3B 3B

1. An aluminum pigment excellent in water resistance having a coatingderived from peroxo-polymolibdate represented by the compositionalformula: MoO₃ .mH ₂O₂ .nH₂O or MoO_(3-m)(O₂)_(m) .nH₂Owherein Mo ismolybdenum, O is oxygen, O≦m≦1 and 1≦n≦2 and comprising at least oneamine selected from alkylamine, allylamine, arylamine, alkanolamine andalkoxylamine:
 2. An aluminum pigment excellent in water resistanceaccording to claim 1 wherein the coating containing 0.02 to 5 parts byweight of Mo and 0.08 to 20 parts by weight of O per 100 parts by weightof aluminum is formed.
 3. An aluminum pigment excellent in waterresistance according to claim 1 or 2 wherein the total added amount ofthe at least one amine selected from alkylamine, allylamine, arylamine,alkanolamine and alkoxylamine is 0.02 to 10 parts by weight per 100parts by weight of aluminum.
 4. An aluminum pigment excellent in waterresistance according to any one of claim 1 to 3 wherein an adsorptionlayer of an organic phosphorus compound is further formed on theinorganic coating.
 5. An aluminum pigment excellent in water resistanceaccording to claim 4 wherein the organic phosphorus compound is an acidphosphate ester derived from an aliphatic monohydric or polyhydricalcohol containing 4 to 18 carbon atoms.
 6. An aluminum pigmentexcellent in water resistance according to claim 4 wherein the organicphosphorus compound is a polymer having an average molecular weightranging from 400 to 10,000.
 7. An aluminum pigment excellent in waterresistance according to any one of claim 4 to 6 wherein an added amountof the organic phosphorus compound is 0.2 to 5 parts by weight per 100parts by weight of aluminum.
 8. A method for preparing an aluminumpigment according to any one of claim 1 to 7 comprising adding at leastone amine selected from alkylamine, allylamine, arylamine, alkanolamineand alkoxylamine together with a solution of a metallic molybdenumdissolved in an aqueous hydrogen oxide and a hydrophilic solvent to analuminum pigment composition containing an organic solvent, stirring andmixing them to form an inorganic coating on a surface of the aluminumpigment, and if necessary adding an organic phosphorus compound beforegetting paste.
 9. A resin composition comprising an aluminum pigmentaccording to any one of claim 1 to 7.